Digital scales and price scanning devices are widely employed in supermarkets and other types of commercial establishments for the processing of items which are being sold on a "price per unit of weight" basis. Such scales and scanning devices frequently constitute parts of a point of sale terminal system which may also include a terminal operated by a cashier. Such point of sale terminal systems normally form part of a check-out operation at which customers queue up for paying for merchandise purchased before leaving the store. In the past, the scales and scanning devices employed in such systems frequently each had their own separate displays. For reason of compactness and economy, it is advantageous to utilize a common display for both the scale and the scanning device. When this is done, it is also advantageous to use a system of indication that is consistent in general meaning for both the scale and the scanning device in order to avoid confusion of the cashier in carrying out these two operations.